190 JOURNAL OF COMPARATIVE NEUROLOGY. 
from the severed tracts of the cord. It seems that nerve cells 
in the injured spinal cord of mammals do not proliferate. The 
ependyma cells lining the central canal may show indications of 
mitotic division (STROEBE); which, when taken in connection 
with the observations of BARFURTH and Caporaso on the regen- 
erative capacity of these cells in the lower vertebrates, is of con- 
siderable theoretical interest. 
Brain of Mammals. 
The healing of wounds in the brains of mammals has been 
studied by numerous investigators, with a view to determining 
whether new nerve tissue is formed. TEpEscHI (31) (1897) 
has given a good account of the reaction of brain tissue to 
various injuries. Wounds were inflicted by him on the 
encephala of rabbits, guinea-pigs, cats and dogs, some by 
plunging a hot needle into the tissue, some by the introduction 
of a foreign body (a piece of paraffin) and others by resection 
of a large piece of a hemisphere. He also studied the effect 
of subdural injection of pathogenic bacteria. Three days after 
the introduction of a foreign body he observed at about I mm. 
distance from ita zone of reaction. Some of the nerve cells in 
this region were altered in form and contained vacuoles, fat 
droplets, and darkly stained nuclei. Many other nerve cells 
were in various stages of karyokinetic division. In isolated 
nerve cells he observed an abnormal arrangement of the chro- 
matic substance of the nucleus, which might be interpreted as a 
phase in the dissolution of the cell. But there were also nor- 
mally constructed karyokinetic figures, which resulted in cell 
proliferation. Mitosis was also seen in the neuroglia and endo- 
thelial cells. Some months after the operation the foreign 
body was surrounded by tissue, consisting chiefly of neuroglia 
but also containing a few ganglion cells and many nerve fibers. 
This nervous tissue is new-formed, he argues, because it is 
found in the place of tissue which had suffered profound de- 
generative changes. He also pictures a nerve cell which has 
sent processes between the lamellae of paraffin and which must 
therefore have been developed since the operation. When re- 
